1. Field of the Invention
The present invention relates to a display device for rotatably supporting a display.
2. Background Art
There is conventionally a case in which the display is rotatably arranged in a vehicle, etc. For example, JP-A-2-86277 (page 2 and FIG. 2) discloses a display device for rotatably supporting the display by a hinge. In the display device of this literature, a leaf spring is arranged in a hinge shaft. Torque for resisting a rotating movement of the display is generated by biasing force of the leaf spring. This torque becomes holding torque for holding the display in a constant position, and also becomes operation torque for generating a responsive feeling when the display is manually rotated and operated. In the display device of this kind, the display is held by the above holding torque. Accordingly, the angle of the display can be steplessly adjusted.
FIG. 10 shows an example when the display device is mounted to a ceiling. In FIG. 10, the display 100 is rotatably supported by a hinge 102 from a storing position to a using range through a passing range. The display is directed to the ceiling in the storing position. When a release button is pushed, the display hangs down by its own weight, and reaches the using range through the passing range. In the using range, torque is generated so as to resist the rotating movement of the display. A user manually rotates the display against the torque until a predetermined desirable position. The display is held in a position in which the user separates a user's hand from the display.
When the display is stored, the user manually rotates the display toward the storing position. In the using range, the torque is applied to the display. However, no torque is applied to the display when the display reaches the passing range. When the display reaches the storing position, the display is locked in its position.
When the torque applied to the display is increased in the above description, the holding force is increased. This is advantageous in vibration resisting performance. However, the operation torque is increased and use dignity (quality) is lowered. Conversely, when the torque is reduced, it is advantageous in use dignity, but the vibration resisting performance is lowered. The magnitude of the torque is conventionally adjusted in consideration of such points.
Thus, the magnitude of the torque within the using range is appropriately set in the conventional display device. However, there were the following problems by a torque change (drop difference) on the boundary of the using range and the passing range. The torque change is conventionally large when the display is moved from the using range to the passing range. Therefore, the torque is suddenly reduced during the storing, and the display is forcibly and suddenly closed. This becomes a cause for making the user lowly feel the dignity. Further, when the display is opened, the torque change at the moving time from the passing range to the using range is large. Therefore, a vibration is generated at the tip of the display at a starting end of the using range. This vibration causes the reduction in dignity.